Multiply by 1-Digit Numbers

Multiplication With Multiples of 10, 100, and 1,000
When multiplying a one-digit number by a multiple of 10, 100, or 1,000, the use of the Associative Property makes it possible to complete the multiplication mentally.

Examples: 3 × 80 = 3 × (8 × 10)= (3 × 8) × 10= 24 × 10= 240

9 × 200 = 9 × (2 × 100)= (9 × 2) × 100= 18 × 100= 1,800

5 × 6,000 = 5 × (6 × 1,000)= (5 × 6) × 1,000= 30 × 1,000= 30,000

The Multiplication Algorithm
Multiplication of a multidigit number by a one-digit number can be completed by using the Distributive Property with the expanded form of the multidigit number.

Distributive Property of Multiplication Over Addition

When two addends are multiplied by a factor, the product is the same as if each addend were multiplied by the factor and the products were added.